This application relates to the art of gas flow controls and, more particularly, to such controls that are capable of providing either a continuous or intermittent flow of gas. The invention is particularly applicable to oxygen conserving devices that are used to supply medicinal oxygen to a patient and will be described with specific reference thereto. However, it will be appreciated that the invention has broader aspects and that at least certain features thereof may be used for other purposes in other gas flow control devices.
Continuous supply of oxygen to a patient wastes oxygen. Therefore, demand valves have been developed to conserve oxygen by cutting off oxygen flow during a patient""s exhalation cycles and starting oxygen flow during a patient""s inhalation cycles. It would be desirable to have a simplified and sensitive oxygen conserving unit that is reliable and can be used with conventional pressure flow regulators without requiring extensive modifications.
An oxygen conserving device in accordance with the present application has a pair of ports that simultaneously are connected with a patient by a dual cannula. The tubes of the dual cannula may be side-by-side or coaxial. In a conserving mode, inhalation by the patient causes a diaphragm valve to open for delivering oxygen to the patient.
The oxygen conserving device is assembled from three sections including a delivery section, a central supply section and a sensing section. The three sections are suitably bolted or otherwise secured together.
The conserving device includes an oxygen delivery port and a sensing port for sensing inhalation by a patient.
The oxygen delivery port delivers oxygen from an oxygen delivery chamber that has an oxygen metering flow inlet. A delivery diaphragm opens and closes the oxygen metering flow inlet, and an oxygen supply pressure chamber is on the opposite side of the delivery diaphragm from the oxygen delivery chamber. Pressurization of the supply pressure chamber moves the delivery diaphragm to a position closing the oxygen metering flow inlet.
An atmospheric vent passage from the supply pressure chamber is normally closed by a sensing diaphragm. The sensing diaphragm responds to patient inhalation by opening the vent passage to vent the supply pressure chamber to atmosphere and cause the delivery diaphragm to open the oxygen metering flow inlet to the oxygen delivery chamber.
A manually operable control valve is selectively operable to provide continuous metering flow of oxygen to the oxygen delivery chamber through a continuous metering flow passage. The sensing and delivery diaphragms may continue to cycle with patient inhalation/exhalation but this does not affect the continuous metering flow when the control valve is in the continuous metering flow position.
An oxygen delivery device in accordance with the present application includes a delivery diaphragm and a sensing diaphragm. The periphery of the delivery diaphragm is sealed between the delivery and supply sections, and the sensing diaphragm is sealed between the supply and sensing sections.
An oxygen delivery chamber is provided in the delivery section on one side of the delivery diaphragm and a supply pressure chamber is provided in the supply section on the opposite side thereof. The oxygen delivery chamber has an oxygen metering flow inlet and an oxygen delivery outlet.
A sensing chamber having a sensing port is provided in the sensing section on one side of the sensing diaphragm, and an atmospheric chamber having an atmospheric vent port is provided in the supply section on the opposite side of the sensing diaphragm.
A vent passage connects the supply pressure chamber with the atmospheric chamber, and the sensing diaphragm normally is biased in a direction to close the vent passage. Pressure in the supply pressure chamber moves the delivery diaphragm to a position closing the oxygen metering flow passage to the oxygen delivery chamber.
The sensing diaphragm is movable to a position opening the vent passage in response to a partial vacuum in the sensing chamber produced by a patient""s inhalation through a cannula connected to the sensing port so that the supply pressure chamber is vented to atmosphere through the vent passage. This causes movement of the delivery diaphragm to a position opening the oxygen metering flow inlet for supplying oxygen to the delivery chamber and through the oxygen delivery outlet to a patient.
It is a principal object of the present application to provide an oxygen conserving device having two ports that simultaneously are connected with a patient by a dual cannula.
It is another object of the application to provide an oxygen conserving device that can be connected with a conventional pressure/flow regulator with minor modification to the regulator.
It is a further object of the application to provide an oxygen conserving device that can be switched between a conserving mode and a continuous metering flow mode.
It also is an object of the invention to provide an oxygen conserving device that is responsive to a patient""s inhalation to open a metering flow inlet to a delivery chamber from which oxygen is supplied to the patient.
It is an additional object of the invention to provide an oxygen conserving device that is reliable in operation, has good sensitivity, and is relatively easy to manufacture, assemble and repair.